China's government must halt economic espionage in cyberspace, U.S. National Security Advisor Susan Rice warned on Monday, days before Chinese President Xi Jinping is due in Washington, D.C., on an official visit.

The issue has become a major thorn in the side of U.S.-China relations in the last year, especially in the wake of the breach of personal information of tens of millions of U.S. government workers at the Office of Personnel Management. The U.S. hasn't publicly accused China of that hack but has done so privately. China denies any involvement.

"This isn’t a mild irritation," Rice said in a speech at George Washington University. "It’s an economic and national security concern to the United States. It puts enormous strain on our bilateral relationship and it is a critical factor in determining the future trajectory of U.S.-China ties."